shebang is ignored by rosrun

edit

I am trying to use a specific python interpreter to run a ros node written by python. For example, I created a package named tmp, and there is a python code named tmp_new.py in catkin_ws/src/tmp/scripts. The content of tmp_new.py is:

#!/usr/bin/python2
import sys
print(sys.executable)

I have edited CMakeLists.txt so that the python executable file can be found:

catkin_install_python(PROGRAMS scripts/tmp_new.py DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION} )

After then, I run catkin_make to build the package, source devel/setup.bash to set the environment, and rosrun tmp tmp_new.py to execute the toy python file.

However, the shebang is completely ignored, and the output is /usr/bin/python3.

To rule out the possibility that my shebang is incorrect, I go into catkin_ws/src/tmp/scripts and run ./tmp_new.py and the shebang is recognized and the output of the program is /usr/bin/python2, which conforms to my expectation.

I am quite confused why this happened? It seems the shebang is completely ignored by rosrun. I also tried to write a launch file, and the behavior is the same as rosrun.

(Some more information: The above is just a toy example which explains the problem I encountered easily. My final goal is to ask ros to execute a python program with a specific virtualenv environment. For example, I created a virtual environment with virtualenv venv, and I set the shebang of the python program to #!/home/xxxx/catkin_ws/venv/bin/python. Rosrun always calls /usr/bin/python3 instead of the virtual environment.)

Environment:

• ROS version: Noetic 1.15.11
• Ubuntu 20.04 x86_64, kernel 5.10.9-051009-generic
• My default python interpreter is /usr/bin/python3
• env | grep ROS > ROS_VERSION=1 ROS_PYTHON_VERSION=3 ROS_PACKAGE_PATH=/home/xxxx/catkin_ws_jetson/src:/home/xxxx/catkin_ws/src:/opt/ros/noetic/share ROSLISP_PACKAGE_DIRECTORIES=/home/xxxx/catkin_ws_jetson/devel/share/common-lisp:/home/xxxx/catkin_ws/devel/share/common-lisp ROS_ETC_DIR=/opt/ros/noetic/etc/ros ROS_MASTER_URI=http://localhost:11311 ROS_ROOT=/opt/ros/noetic/share/ros ROS_DISTRO=noetic